U.S. Pat. No. 4,715,952 issued Dec. 29, 1987 and assigned to the assignee of this invention discloses a reverse osmosis water purification element and cartridge which is similar to the present invention but which requires the services of a skilled and knowledgeable technician in order to replace used filter units with new units without damaging the delicate membrane which forms an essential part of such units.
U.S. Pat. No. 4,874,514 issued Oct. 17, 1989 and assigned to the assignee of this invention discloses a tubular element for reverse osmosis water purification. The element of this patent can be used in the practice of the present invention or a slightly different filter unit may be used as is disclosed in this application.